Cisco Catalyst comparison

I'm looking for a good comparison chart or article which compares different catalyst switches, particularly:

1) 2950
2) 3550
3) 4506
4) 4507

The comparison should include stuff such as what features are supported, number of slots etc. not anything overly complicated. Does anyone know of a good source without going to the cisco site and scavenging differences? Or perhaps someone can give me important points which diffentiate one switch from another on important matters?

Thanks alot for your time and thought guys